diff --git a/src/Sapl/Transform/Let.icl b/src/Sapl/Transform/Let.icl
index ea6289b2a9c77245a6a38c98865cc29d03079382..148decdb13e6e00417c648060db3bb055f7df24a 100644
--- a/src/Sapl/Transform/Let.icl
+++ b/src/Sapl/Transform/Let.icl
@@ -4,7 +4,7 @@ import StdList, StdFunc, StdTuple, StdBool
 import Sapl.SaplStruct
 
 from Data.Set import qualified newSet, fromList, toList, member, difference, insert, filter, delete, null
-from Data.Set import :: Set
+from Data.Set import :: Set, instance Foldable Set
 from Data.Map import qualified fromList, get
 
 instance == SaplVar
@@ -52,5 +52,3 @@ where
 			| 'Data.Set'.null ('Data.Set'.filter (\e = snd e == m) edges)
 				= (edges, [m:out])
 				= (edges, out)
-				
-				
\ No newline at end of file
diff --git a/src/Sapl/Transform/TailRecursion.icl b/src/Sapl/Transform/TailRecursion.icl
index 68f6cda1c6803870b84dcb70a421a533b604cc49..b15ef9f8c10cb18de2d42f2ac4207df3bb8f1837 100644
--- a/src/Sapl/Transform/TailRecursion.icl
+++ b/src/Sapl/Transform/TailRecursion.icl
@@ -4,7 +4,7 @@ import StdList, StdFunc, StdTuple, StdBool
 import Sapl.SaplStruct
 
 from Data.Set import qualified newSet, fromList, toList, member, difference, insert, filter, delete, null
-from Data.Set import :: Set
+from Data.Set import :: Set, instance Foldable Set
 from Data.Map import qualified fromList, get
 
 instance == SaplVar
@@ -52,5 +52,3 @@ where
 			| 'Data.Set'.null ('Data.Set'.filter (\e = snd e == m) edges)
 				= (edges, [m:out])
 				= (edges, out)
-				
-				
\ No newline at end of file